Due to actualization of environmental problems in recent years, hybrid cars and electric cars have spread. Further, as an air-conditioning device which is applicable to such a vehicle, there has been developed an air-conditioning device which includes a compressor to compress and discharge a refrigerant, a radiator disposed on a vehicle interior side to let the refrigerant radiate heat, a heat absorber disposed on the vehicle interior side to let the refrigerant absorb heat, and an outdoor heat exchanger disposed outside the vehicle interior to let the refrigerant radiate or absorb heat, and which changes and executes a heating operation of letting the refrigerant discharged from the compressor radiate heat in the radiator and letting the refrigerant from which the heat has been radiated in this radiator absorb heat in the outdoor heat exchanger, a dehumidifying and heating operation or a dehumidifying and cooling operation of letting the refrigerant discharged from the compressor radiate heat in the radiator and letting the refrigerant from which the heat has been radiated in the radiator absorb heat in the heat absorber, and a cooling operation of letting the refrigerant discharged from the compressor radiate heat in the outdoor heat exchanger and letting the refrigerant absorb heat in the heat absorber.
In this case, an accumulator is provided on a refrigerant suction side of the compressor, the refrigerant is once stored in this accumulator to separate a gas and a liquid, and a gas refrigerant is sucked into the compressor to prevent or inhibit the liquid from being returned to the compressor (e.g., Patent Document 1).